package com.chixing;

import org.junit.Test;

import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;

public class a {

    @Test
    public void xx(){
//        char a = '0';
//        int b= (int)a;
//        System.out.println(b);
//        Map hashMap = new HashMap<>();
//        Map hashTable = new Hashtable();
//        hashMap.put(null,"1");
//        hashTable.put(null,"2");
//        hashMap.put("3",null);
//        hashTable.put("4",null);
    }
}
